RubyGems 1.3.7 or higher is required with following limitations :
Rails 2.3.5 will fail with RubyGems 1.5.0 or later, stick to previous versions of RubyGems !
Rails 2.3.11 will fail with RubyGems 1.7.0 or later, stick to previous versions of RubyGems !

# gem install passenger
# passenger-install-apache2-module
Welcome to the Phusion Passenger Apache 2 module installer, v3.0.9.
This installer will guide you through the entire installation process. It
shouldn't take more than 3 minutes in total.
Here's what you can expect from the installation process:
1. The Apache 2 module will be installed for you.
2. You'll learn how to configure Apache.
3. You'll learn how to deploy a Ruby on Rails application.
Don't worry if anything goes wrong. This installer will advise you on how to
solve any problems.
Press Enter to continue, or Ctrl-C to abort. <= エンター押下
--------------------------------------------
Checking for required software...
* GNU C++ compiler... found at /usr/bin/g++
* Curl development headers with SSL support... found
* OpenSSL development headers... found
* Zlib development headers... found
* Ruby development headers... found
* OpenSSL support for Ruby... found
* RubyGems... found
* Rake... found at /usr/bin/rake
* rack... found
* Apache 2... found at /usr/sbin/httpd
* Apache 2 development headers... not found
* Apache Portable Runtime (APR) development headers... not found
* Apache Portable Runtime Utility (APU) development headers... not found
Some required software is not installed.
But don't worry, this installer will tell you how to install them.
Press Enter to continue, or Ctrl-C to abort. <= 必須モジュールがそろってないのでCtrl-C